"___ Window" (1955 Hitchcock film) (4)
(Other definitions for rear that I've seen before include "parent" , "Posterior" , "Rare at the back" , "what can be brought up, finally" , "The back part of something" .)
'window' is the definition.
(bay window is a kind of window)
This is the entire clue.
(Other definitions for bay that I've seen before include "Sea inlet" , "Broad curved inlet" , "Indentation of a shoreline" , "Botany, Galway or Tampa" , "Laurel tree - bark" .)